Supported Iron Phthalocyanine As An Activater Of Perxymonosulfate For The Degradation Of Norfloxacin

The catalytic activity of transition metal ions for the activation of perxymonosulfate（PMS）follows the following order:Co²⁺>Ru³⁺>Fe²⁺>Ce³⁺>V³⁺>Mn²⁺>Fe³⁺>Ni²⁺.Although the catalytic activity of Fe²⁺for PMS is lower than that of Co²⁺and Ru³⁺,Fe²⁺has no/low toxicity and low price..Metal phthalocyanine（MPc）has a unique two-dimensional structure with 18π-electron aromatic porphyrin synthetic analogues,and its catalytic activity is determined by the central metal.Therefore,it is more concerned to construct environmentally friendly catalyst based on Fe Pc.However,metal phthalocyanine is easy to agglomerate in aqueous solution,which is not conducive to the exposure of metal center.The catalytic performance of the supported metal phthalocyanine can be improved by selecting suitable support.Graphene has a large specific surface area and good conductivity.The carrier can not only enhance the adsorption of organic pollutants,but also improve the dispersion of Fe Pc and the circulation of Fe（III）/Fe（II）.Manganese dioxide（Mn O₂）has the ability of activating PMS.The combination of manganese dioxide and Fe Pc not only can inhibit the agglomeration of Fe Pc,but also the electron transfer between Fe and Mn bimetallic can activate PMS.Therefore,the graphene supported phthalocyanine iron and manganese dioxide supported phthalocyanine iron were prepared,and used to activate PMS to degrade norfloxacin（NOR）.The main results are as follows:（1）Graphene（BG）was prepared from the ball milling of flake graphite with potassium persulfate as milling agent.Using ball milled graphene（BG）and Fe Pc as raw materials and ethanol as solvent,BG/Fe Pc composite catalyst was prepared under ultrasonic irradiation.At p H 7 and PMS dosage of 0.16 mmo L^-1,the catalyst(0.01 g L^-1)could completely degrade NOR(10 mg L^-1)in 20 min,and its pseudo first reaction rate constant k is 0.65 min^-1,being 71 times of Fe Pc(0.0092 min^-1).In addition,the values of k on BG/Fe Pc were by 4 and 16 times higher than those for Fe Pc using graphene oxide（GO）prepared by Hummers and reduced GO（RGO）as the support,respectively.EPR and quenching experiments showed that the main active species involved in the degradation of NOR was ¹O₂,O₂^·-,SO₄^·-and·OH also contributed.The characterizations using FT-IR,Raman and XPS show that BG can donor the electron pairs to Fe Pc,increasing the electron density of central Fe and BG/Fe Pc,and the BG/Fe Pc exhibts the strong affinity towdars the adsorption of PMS.Taken together with the high dispersion of Fe Pc on BG,BG/Fe Pc is highly efficient in the activation of PMS.（2）Mn O₂/Fe Pc composite catalyst was prepared by ball milling method withγ-Mn O₂ and Fe Pc as raw materials.The results of XRD showed that the crystal form of Mn O₂ did not change,and XPS showed that the electron of Fe Pc was transferred to Mn O₂in Mn O₂/Fe Pc composite catalyst.The catalyst can also effectively activate PMS to degrade NOR.Under the conditions of p H 7 and 0.16 mmo L^-1 PMS,it can almost completely degrade NOR(10 mg L^-1)in 20 min,and the degradation rate constant k is0.62 min^-1.However,when Fe SO₄,Fe Cl₂ and EDTA-Fe were used as iron sources,the ability of Mn O₂ to activate PMS to degrade NOR was not significantly improved.Compared with Mn O₂ and Fe Pc,the mass specific activity of Mn O₂/Fe Pc is increased by15 and 68 times,respectively.The results show that the introduction of Fe Pc can significantly improve the activity of Mn O₂.EPR and quenching experiments show that the main active species is ¹O₂ in Mn O₂/Fe Pc system.In addition,the good reusability of Mn O₂/Fe Pc/PMS may be due to the valence cycle of Mn（IV）/Mn（III）and Fe（III）/Fe（II）.The degradation products were analyzed by LC-MS,and the degradation pathway of NOR was elucidated,which included defluorination and transformation of piperazine ring.